Various sensors such as optical sensor, capacitance-type sensor and pressure sensor are used as means for sensing the pulse rate and the respiration rate of a living body such as human body. At present, the optical sensor is most commonly used.
The conventional massaging machines merely conduct massaging operation according to a predetermined program. In recent years, however, a massaging machine programmed to sense a biosignal such as pulse rate and respiration rate of a user to be massaged and to conduct massaging operation, i.e., treatment, according to the sensing result is used in practical applications.
Conventionally, however, a sensor of the above type must be attached somewhere on the user's body in order to detect the pulse rate and the respiration rate of the human body. Accordingly, the human body is placed under restraint in some way, which is extremely bothersome in use.
A massaging machine has been developed which is capable of detecting the above biosignal by merely requiring the user to sit on the massaging machine without using a sensor that restrains the human body. For example, such a massaging machine is disclosed in Japanese Laid-Open Publication No. 9-248284.
A conventional chair-type massaging machine of this type uses an optical sensor. The optical sensor is formed from a flexible optical fiber having its one end connected to a light-emitting portion and the other end connected to a light-receiving portion, and the optical fiber is used in contact with the human body.
More specifically, the optical fiber in contact with the human body is bent by slight movement of the human body like pulsation, respiration and the like, thereby varying the quantity of light transmitted from the light-emitting portion to the light-receiving portion through the optical fiber. A biosignal such as pulse rate and respiration rate can be obtained by sensing such variation in light quantity.
The above conventional chair-type massaging machine has such a mechanical structure that the user's weight is intensively placed on one part of the seat surface of the massaging machine when the user is seated thereon. The optical sensor is mounted so that a part of the optical fiber contacts that part. This massaging machine thus detects variation in light quantity caused by deformation of the optical fiber resulting from the body movement of the user, and filters the detection signal to extract a desired biosignal such as pulse rate and respiration rate.
However, the conventional chair-type massaging machine using such an optical sensor has a complicated mechanical structure for transmitting the body movement of the user intensively to the optical fiber, resulting in increased manufacturing costs.
Moreover, extracting the pulse rate and the respiration rate, i.e., physical movement of the human body (mixture of vertical and horizontal movements), by filtering is sometimes difficult in terms of signal processing. Therefore, biosignal detection based on variation in light quantity is problematic in terms of detection accuracy.
It is an object of the present invention to provide a biosignal sensing device capable of accurately sensing a biosignal such as pulse rate and respiration rate without restraining a living body.
It is another object of the present invention to provide a massaging machine incorporating such a biosignal sensing device and thus having a simplified structure and suppressing increase in manufacturing costs.
It is still another object of the present invention to provide a massaging machine incorporating such a biosignal sensing device and thus capable of providing treatment based on a biosignal detected with high accuracy.